567 lines
14 KiB
C
567 lines
14 KiB
C
/* search.c -- How to search large bodies of text. */
|
||
|
||
/* This file is part of GNU Info, a program for reading online documentation
|
||
stored in Info format.
|
||
|
||
Copyright (C) 1993 Free Software Foundation, Inc.
|
||
|
||
This program is free software; you can redistribute it and/or modify
|
||
it under the terms of the GNU General Public License as published by
|
||
the Free Software Foundation; either version 2, or (at your option)
|
||
any later version.
|
||
|
||
This program is distributed in the hope that it will be useful,
|
||
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
GNU General Public License for more details.
|
||
|
||
You should have received a copy of the GNU General Public License
|
||
along with this program; if not, write to the Free Software
|
||
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
|
||
|
||
Written by Brian Fox (bfox@ai.mit.edu). */
|
||
|
||
#include <ctype.h>
|
||
#include <sys/types.h>
|
||
#include <sys/stat.h>
|
||
#include "general.h"
|
||
#include "search.h"
|
||
#include "nodes.h"
|
||
|
||
#if !defined (NULL)
|
||
# define NULL 0x0
|
||
#endif /* !NULL */
|
||
|
||
/* The search functions take two arguments:
|
||
|
||
1) a string to search for, and
|
||
|
||
2) a pointer to a SEARCH_BINDING which contains the buffer, start,
|
||
and end of the search.
|
||
|
||
They return a long, which is the offset from the start of the buffer
|
||
at which the match was found. An offset of -1 indicates failure. */
|
||
|
||
/* A function which makes a binding with buffer and bounds. */
|
||
SEARCH_BINDING *
|
||
make_binding (buffer, start, end)
|
||
char *buffer;
|
||
long start, end;
|
||
{
|
||
SEARCH_BINDING *binding;
|
||
|
||
binding = (SEARCH_BINDING *)xmalloc (sizeof (SEARCH_BINDING));
|
||
binding->buffer = buffer;
|
||
binding->start = start;
|
||
binding->end = end;
|
||
binding->flags = 0;
|
||
|
||
return (binding);
|
||
}
|
||
|
||
/* Make a copy of BINDING without duplicating the data. */
|
||
SEARCH_BINDING *
|
||
copy_binding (binding)
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
SEARCH_BINDING *copy;
|
||
|
||
copy = make_binding (binding->buffer, binding->start, binding->end);
|
||
copy->flags = binding->flags;
|
||
return (copy);
|
||
}
|
||
|
||
|
||
/* **************************************************************** */
|
||
/* */
|
||
/* The Actual Searching Functions */
|
||
/* */
|
||
/* **************************************************************** */
|
||
|
||
/* Search forwards or backwards for the text delimited by BINDING.
|
||
The search is forwards if BINDING->start is greater than BINDING->end. */
|
||
long
|
||
search (string, binding)
|
||
char *string;
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
long result;
|
||
|
||
/* If the search is backwards, then search backwards, otherwise forwards. */
|
||
if (binding->start > binding->end)
|
||
result = search_backward (string, binding);
|
||
else
|
||
result = search_forward (string, binding);
|
||
|
||
return (result);
|
||
}
|
||
|
||
/* Search forwards for STRING through the text delimited in BINDING. */
|
||
long
|
||
search_forward (string, binding)
|
||
char *string;
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
register int c, i, len;
|
||
register char *buff, *end;
|
||
char *alternate = (char *)NULL;
|
||
|
||
len = strlen (string);
|
||
|
||
/* We match characters in the search buffer against STRING and ALTERNATE.
|
||
ALTERNATE is a case reversed version of STRING; this is cheaper than
|
||
case folding each character before comparison. Alternate is only
|
||
used if the case folding bit is turned on in the passed BINDING. */
|
||
|
||
if (binding->flags & S_FoldCase)
|
||
{
|
||
alternate = savestring (string);
|
||
|
||
for (i = 0; i < len; i++)
|
||
{
|
||
if (islower (alternate[i]))
|
||
alternate[i] = toupper (alternate[i]);
|
||
else if (isupper (alternate[i]))
|
||
alternate[i] = tolower (alternate[i]);
|
||
}
|
||
}
|
||
|
||
buff = binding->buffer + binding->start;
|
||
end = binding->buffer + binding->end + 1;
|
||
|
||
while (buff < (end - len))
|
||
{
|
||
for (i = 0; i < len; i++)
|
||
{
|
||
c = buff[i];
|
||
|
||
if ((c != string[i]) && (!alternate || c != alternate[i]))
|
||
break;
|
||
}
|
||
|
||
if (!string[i])
|
||
{
|
||
if (alternate)
|
||
free (alternate);
|
||
if (binding->flags & S_SkipDest)
|
||
buff += len;
|
||
return ((long) (buff - binding->buffer));
|
||
}
|
||
|
||
buff++;
|
||
}
|
||
|
||
if (alternate)
|
||
free (alternate);
|
||
|
||
return ((long) -1);
|
||
}
|
||
|
||
/* Search for STRING backwards through the text delimited in BINDING. */
|
||
long
|
||
search_backward (input_string, binding)
|
||
char *input_string;
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
register int c, i, len;
|
||
register char *buff, *end;
|
||
char *string;
|
||
char *alternate = (char *)NULL;
|
||
|
||
len = strlen (input_string);
|
||
|
||
/* Reverse the characters in the search string. */
|
||
string = (char *)xmalloc (1 + len);
|
||
for (c = 0, i = len - 1; input_string[c]; c++, i--)
|
||
string[i] = input_string[c];
|
||
|
||
string[c] = '\0';
|
||
|
||
/* We match characters in the search buffer against STRING and ALTERNATE.
|
||
ALTERNATE is a case reversed version of STRING; this is cheaper than
|
||
case folding each character before comparison. ALTERNATE is only
|
||
used if the case folding bit is turned on in the passed BINDING. */
|
||
|
||
if (binding->flags & S_FoldCase)
|
||
{
|
||
alternate = savestring (string);
|
||
|
||
for (i = 0; i < len; i++)
|
||
{
|
||
if (islower (alternate[i]))
|
||
alternate[i] = toupper (alternate[i]);
|
||
else if (isupper (alternate[i]))
|
||
alternate[i] = tolower (alternate[i]);
|
||
}
|
||
}
|
||
|
||
buff = binding->buffer + binding->start;
|
||
end = binding->buffer + binding->end;
|
||
|
||
while (buff > end + len)
|
||
{
|
||
for (i = 0; i < len; i++)
|
||
{
|
||
c = *(buff - i);
|
||
|
||
if (c != string[i] && (alternate && c != alternate[i]))
|
||
break;
|
||
}
|
||
|
||
if (!string[i])
|
||
{
|
||
free (string);
|
||
if (alternate)
|
||
free (alternate);
|
||
|
||
if (binding->flags & S_SkipDest)
|
||
buff -= len;
|
||
return ((long) (1 + (buff - binding->buffer)));
|
||
}
|
||
|
||
buff--;
|
||
}
|
||
|
||
free (string);
|
||
if (alternate)
|
||
free (alternate);
|
||
|
||
return ((long) -1);
|
||
}
|
||
|
||
/* Find STRING in LINE, returning the offset of the end of the string.
|
||
Return an offset of -1 if STRING does not appear in LINE. The search
|
||
is bound by the end of the line (i.e., either NEWLINE or 0). */
|
||
int
|
||
string_in_line (string, line)
|
||
char *string, *line;
|
||
{
|
||
register int end;
|
||
SEARCH_BINDING binding;
|
||
|
||
/* Find the end of the line. */
|
||
for (end = 0; line[end] && line[end] != '\n'; end++);
|
||
|
||
/* Search for STRING within these confines. */
|
||
binding.buffer = line;
|
||
binding.start = 0;
|
||
binding.end = end;
|
||
binding.flags = S_FoldCase | S_SkipDest;
|
||
|
||
return (search_forward (string, &binding));
|
||
}
|
||
|
||
/* Return non-zero if STRING is the first text to appear at BINDING. */
|
||
int
|
||
looking_at (string, binding)
|
||
char *string;
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
long search_end;
|
||
|
||
search_end = search (string, binding);
|
||
|
||
/* If the string was not found, SEARCH_END is -1. If the string was found,
|
||
but not right away, SEARCH_END is != binding->start. Otherwise, the
|
||
string was found at binding->start. */
|
||
return (search_end == binding->start);
|
||
}
|
||
|
||
/* **************************************************************** */
|
||
/* */
|
||
/* Small String Searches */
|
||
/* */
|
||
/* **************************************************************** */
|
||
|
||
/* Function names that start with "skip" are passed a string, and return
|
||
an offset from the start of that string. Function names that start
|
||
with "find" are passed a SEARCH_BINDING, and return an absolute position
|
||
marker of the item being searched for. "Find" functions return a value
|
||
of -1 if the item being looked for couldn't be found. */
|
||
|
||
/* Return the index of the first non-whitespace character in STRING. */
|
||
int
|
||
skip_whitespace (string)
|
||
char *string;
|
||
{
|
||
register int i;
|
||
|
||
for (i = 0; string && whitespace (string[i]); i++);
|
||
return (i);
|
||
}
|
||
|
||
/* Return the index of the first non-whitespace or newline character in
|
||
STRING. */
|
||
int
|
||
skip_whitespace_and_newlines (string)
|
||
char *string;
|
||
{
|
||
register int i;
|
||
|
||
for (i = 0; string && (whitespace (string[i]) || string[i] == '\n'); i++);
|
||
return (i);
|
||
}
|
||
|
||
/* Return the index of the first whitespace character in STRING. */
|
||
int
|
||
skip_non_whitespace (string)
|
||
char *string;
|
||
{
|
||
register int i;
|
||
|
||
for (i = 0; string && !whitespace (string[i]); i++);
|
||
return (i);
|
||
}
|
||
|
||
/* Return the index of the first non-node character in STRING. Note that
|
||
this function contains quite a bit of hair to ignore periods in some
|
||
special cases. This is because we here at GNU ship some info files which
|
||
contain nodenames that contain periods. No such nodename can start with
|
||
a period, or continue with whitespace, newline, or ')' immediately following
|
||
the period. If second argument NEWLINES_OKAY is non-zero, newlines should
|
||
be skipped while parsing out the nodename specification. */
|
||
int
|
||
skip_node_characters (string, newlines_okay)
|
||
char *string;
|
||
int newlines_okay;
|
||
{
|
||
register int c, i = 0;
|
||
int paren_seen = 0;
|
||
int paren = 0;
|
||
|
||
/* Handle special case. This is when another function has parsed out the
|
||
filename component of the node name, and we just want to parse out the
|
||
nodename proper. In that case, a period at the start of the nodename
|
||
indicates an empty nodename. */
|
||
if (string && *string == '.')
|
||
return (0);
|
||
|
||
if (string && *string == '(')
|
||
{
|
||
paren++;
|
||
paren_seen++;
|
||
i++;
|
||
}
|
||
|
||
for (; string && (c = string[i]); i++)
|
||
{
|
||
if (paren)
|
||
{
|
||
if (c == '(')
|
||
paren++;
|
||
else if (c == ')')
|
||
paren--;
|
||
|
||
continue;
|
||
}
|
||
|
||
/* If the character following the close paren is a space or period,
|
||
then this node name has no more characters associated with it. */
|
||
if (c == '\t' ||
|
||
c == ',' ||
|
||
c == INFO_TAGSEP ||
|
||
((!newlines_okay) && (c == '\n')) ||
|
||
((paren_seen && string[i - 1] == ')') &&
|
||
(c == ' ' || c == '.')) ||
|
||
(c == '.' &&
|
||
((!string[i + 1]) ||
|
||
(whitespace_or_newline (string[i + 1])) ||
|
||
(string[i + 1] == ')'))))
|
||
break;
|
||
}
|
||
return (i);
|
||
}
|
||
|
||
/* Unix doesn't have stricmp () functions. */
|
||
int
|
||
stricmp (string1, string2)
|
||
char *string1, *string2;
|
||
{
|
||
char ch1, ch2;
|
||
|
||
for (;;)
|
||
{
|
||
ch1 = *string1++;
|
||
ch2 = *string2++;
|
||
|
||
if (!(ch1 | ch2))
|
||
return (0);
|
||
|
||
ch1 = info_toupper (ch1);
|
||
ch2 = info_toupper (ch2);
|
||
|
||
if (ch1 != ch2)
|
||
return (ch1 - ch2);
|
||
}
|
||
}
|
||
|
||
/* Compare at most COUNT characters from string1 to string2. Case
|
||
doesn't matter. */
|
||
int
|
||
strnicmp (string1, string2, count)
|
||
char *string1, *string2;
|
||
int count;
|
||
{
|
||
register char ch1, ch2;
|
||
|
||
while (count)
|
||
{
|
||
ch1 = *string1++;
|
||
ch2 = *string2++;
|
||
|
||
ch1 = info_toupper (ch1);
|
||
ch2 = info_toupper (ch2);
|
||
|
||
if (ch1 == ch2)
|
||
count--;
|
||
else
|
||
break;
|
||
}
|
||
return (count);
|
||
}
|
||
|
||
/* **************************************************************** */
|
||
/* */
|
||
/* Searching FILE_BUFFER's */
|
||
/* */
|
||
/* **************************************************************** */
|
||
|
||
/* Return the absolute position of the first occurence of a node separator in
|
||
BINDING-buffer. The search starts at BINDING->start. Return -1 if no node
|
||
separator was found. */
|
||
long
|
||
find_node_separator (binding)
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
register long i;
|
||
char *body;
|
||
|
||
body = binding->buffer;
|
||
|
||
/* A node is started by [^L]^_[^L]\n. That is to say, the C-l's are
|
||
optional, but the DELETE and NEWLINE are not. This separator holds
|
||
true for all separated elements in an Info file, including the tags
|
||
table (if present) and the indirect tags table (if present). */
|
||
for (i = binding->start; i < binding->end - 1; i++)
|
||
if (((body[i] == INFO_FF && body[i + 1] == INFO_COOKIE) &&
|
||
(body[i + 2] == '\n' ||
|
||
(body[i + 2] == INFO_FF && body[i + 3] == '\n'))) ||
|
||
((body[i] == INFO_COOKIE) &&
|
||
(body[i + 1] == '\n' ||
|
||
(body[i + 1] == INFO_FF && body[i + 2] == '\n'))))
|
||
return (i);
|
||
return (-1);
|
||
}
|
||
|
||
/* Return the length of the node separator characters that BODY is
|
||
currently pointing at. */
|
||
int
|
||
skip_node_separator (body)
|
||
char *body;
|
||
{
|
||
register int i;
|
||
|
||
i = 0;
|
||
|
||
if (body[i] == INFO_FF)
|
||
i++;
|
||
|
||
if (body[i++] != INFO_COOKIE)
|
||
return (0);
|
||
|
||
if (body[i] == INFO_FF)
|
||
i++;
|
||
|
||
if (body[i++] != '\n')
|
||
return (0);
|
||
|
||
return (i);
|
||
}
|
||
|
||
/* Return the number of characters from STRING to the start of
|
||
the next line. */
|
||
int
|
||
skip_line (string)
|
||
char *string;
|
||
{
|
||
register int i;
|
||
|
||
for (i = 0; string && string[i] && string[i] != '\n'; i++);
|
||
|
||
if (string[i] == '\n')
|
||
i++;
|
||
|
||
return (i);
|
||
}
|
||
|
||
/* Return the absolute position of the beginning of a tags table in this
|
||
binding starting the search at binding->start. */
|
||
long
|
||
find_tags_table (binding)
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
SEARCH_BINDING search;
|
||
long position;
|
||
|
||
search.buffer = binding->buffer;
|
||
search.start = binding->start;
|
||
search.end = binding->end;
|
||
search.flags = S_FoldCase;
|
||
|
||
while ((position = find_node_separator (&search)) != -1 )
|
||
{
|
||
search.start = position;
|
||
search.start += skip_node_separator (search.buffer + search.start);
|
||
|
||
if (looking_at (TAGS_TABLE_BEG_LABEL, &search))
|
||
return (position);
|
||
}
|
||
return (-1);
|
||
}
|
||
|
||
/* Return the absolute position of the node named NODENAME in BINDING.
|
||
This is a brute force search, and we wish to avoid it when possible.
|
||
This function is called when a tag (indirect or otherwise) doesn't
|
||
really point to the right node. It returns the absolute position of
|
||
the separator preceding the node. */
|
||
long
|
||
find_node_in_binding (nodename, binding)
|
||
char *nodename;
|
||
SEARCH_BINDING *binding;
|
||
{
|
||
register long position;
|
||
register int offset, namelen;
|
||
SEARCH_BINDING search;
|
||
|
||
namelen = strlen (nodename);
|
||
|
||
search.buffer = binding->buffer;
|
||
search.start = binding->start;
|
||
search.end = binding->end;
|
||
search.flags = 0;
|
||
|
||
while ((position = find_node_separator (&search)) != -1)
|
||
{
|
||
search.start = position;
|
||
search.start += skip_node_separator (search.buffer + search.start);
|
||
|
||
offset = string_in_line (INFO_NODE_LABEL, search.buffer + search.start);
|
||
|
||
if (offset == -1)
|
||
continue;
|
||
|
||
search.start += offset;
|
||
search.start += skip_whitespace (search.buffer + search.start);
|
||
offset = skip_node_characters
|
||
(search.buffer + search.start, DONT_SKIP_NEWLINES);
|
||
|
||
/* Notice that this is an exact match. You cannot grovel through
|
||
the buffer with this function looking for random nodes. */
|
||
if ((offset == namelen) &&
|
||
(search.buffer[search.start] == nodename[0]) &&
|
||
(strncmp (search.buffer + search.start, nodename, offset) == 0))
|
||
return (position);
|
||
}
|
||
return (-1);
|
||
}
|